Cannula with introducer, needle protecting guard and blood collecting system

ABSTRACT

A cannula introducing device comprises an elongate body ( 10 ) having a needle ( 12 ) projecting from a front end, an operating element ( 24 ) for displacement longitudinally of the body ( 10 ), a plunger ( 16 ) disposed at the front end of the body ( 10 ), and a coupling means ( 18 ), such as a flexible wire, coupling the operating element ( 24 ) and the plunger ( 16 ), arranged so that retraction of the operating element ( 24 ) serves to advance the plunger ( 16 ) over the needle ( 12 ) and so advance the cannula ( 30 ) which is disposed over the needle.

The present invention relates to medical devices including devices forintroducing a cannula into a patient's blood vessel and for collecting asample of blood or other bodily fluid.

Intravenous cannulation is an important procedure particularly in themanagement of acutely ill patients. The procedure is carried out using aneedle inserted through the cannula, with the tip of the needleprojecting from the forward end of the cannula, then inserting the tipof the needle into an artery or vein, and finally advancing the cannulaover the tip of the needle to introduce its forward end into the bloodvessel, then withdrawing the needle. This procedure requires very finehand control and considerable practise on the part of the doctorcarrying it out. Moreover, cannulation is occasionally complicated andin any event takes time and places the patient under considerablestress.

Cannula introducing devices have hitherto been arranged for user to movethe cannula forwardly, over the tip of the needle, using the indexfinger. This forward movement of the cannula must be performed swiftlyonce the tip of the needle has entered the lumen of the blood vessel:any slight movement of the tip of the needle in the blood vessel lumenmay result in puncture and failed cannulation; any withdrawal of the tipof the needle, prior to cannula placement in the lumen, will also resultin failure. U.S. Pat. No. 5,338,306 is directed to a cannula introducingdevice which uses either a mechanical spring or a compressed air spring,released by the user once the tip of the needle has been inserted intothe blood vessel, to advance the cannula over the needle and into theblood vessel.

I have now devised a cannula introducing device which is reliable to useand does not include any form of spring, at least for initialintroduction of the cannula into the blood vessel.

In accordance with the present invention, there is provided a cannulaintroducing device which comprises an elongate body having a needleprojecting from one end thereof, an operating element mounted to saidbody for displacement longitudinally thereof, a plunger disposed at saidone end of the body, and means coupling said operating element and saidplunger and arranged so that displacement of said operating element awayfrom said one end of the body causes displacement of said coupling meansto advance said plunger along said needle.

In use, a cannula is slipped over the needle to abut the plunger of thedevice, with the tip of the needle projecting from the forward end ofthe cannula. Then the user grips the body of the device and brings theassembly up to the patient to insert the tip of the needle into a bloodvessel. The user then retracts the operating element of the device,typically using the index finger, to advance the plunger and so advancethe forward end of the cannula over the tip of the needle and into theblood vessel. The device can then be withdrawn, to withdraw the needle,firstly from the blood vessel and then from the cannula, leaving thecannula inserted into the blood vessel: as the device is withdrawn, theretracting movement of the manual operating element may be continued, tocontinue the advancement of the plunger: preferably the arrangement issuch that the plunger will advance far enough to cover the tip of theneedle, and so prevent any possible needle stick injuries.

In an alternative embodiment, the plunger is arranged to be advanced aninitial distance by the retracting displacement of the operating element(preferably sufficient to advance the tip of the cannula over the tip ofthe needle and provide initial introduction of the tip of the cannulainto the blood vessel), and the device further comprises a spring(either a mechanical spring or a gas spring) which then serves toadvance the plunger through a further distance: preferably the plunger,in its fully-advanced position, covers the tip of the needle, to preventany possible needle-stick injuries.

Preferably the device includes means for preventing the plunger beingretracted after it has been advanced: this prevents the device beingre-used, with the risk of spreading infection. Preferably, in order toprevent the plunger being retracted, the coupling means is provided witha series of ratchet serrations which co-operate with a tooth orprojection with which the body of the device is provided.

The coupling means may comprise an elongate flexible element extendingalong a guideway of said body, between the operating element and thecannula-advancing plunger, the elongate flexible element being displacedlongitudinally of itself as the operating element is retracted. Thiselongate flexible element may be arranged to push the plunger forwardly,or it may be arranged to pull on a rearward extension of the plunger topull the plunger forwardly.

Preferably the guideway comprises a groove or channel formed in the bodyof the device, the operating element being engaged into and retained bythis groove or channel for sliding movement along it. Preferably theoperating element comprises a member which projects outwardly from theguide groove or channel, for the user to engage manually, typically withthe index finger.

In one embodiment the guideway further comprises a passage having afirst portion which extends from the rear end of the guide groove orchannel and curves round to a second portion which extends forwardly tothe front end of the body. In another embodiment, the guideway has afirst portion which extends from the forward end of the guide groove orchannel and curves round to a second portion which extends rearwardly ofthe body. Preferably the latter, second portion of the passage isdisposed in or adjacent a surface of the body remote from or oppositethe surface in which the guide groove or channel is formed.

The elongate element which interconnects the operating element and theplunger may comprise a wire, preferably of a flat cross-sectionalprofile.

Preferably the body of the device is arranged to receive ablood-collecting container for receiving blood which flows along theneedle of the device when its tip is inserted into a blood vessel.Preferably the device includes an internal chamber to receive bloodthrough the needle, this chamber being provided with a plunger which isretracted, upon retraction of the operating element of the device, or ofa secondary operating element associated therewith, for a piercingneedle of this plunger to pierce a membrane closing the end of theblood-collecting container: preferably the blood-collecting container ispre-evacuated or otherwise arranged to provide a vacuum so that theblood is drawn into the container.

Also in accordance with the present invention, there is provided adevice for collecting a sample of blood or other fluid, the devicecomprising an elongate body having a needle projecting from one endthereof, the body having an interior compartment for receiving afluid-collecting container and having a plunger disposed therein, thedevice further comprising an operating element arranged for displacementlongitudinally of said body away from said one end thereof, in order todisplace said plunger and for a piercing needle provided on said plungerto pierce a membrane which closes said container.

The device may be arranged to create a vacuum in the fluid-collectingcontainer, as the container is inserted longitudinally into the devicebody. For example, the interior compartment of the device body may beprovided with an elongate pusher element directed to pierce the membraneof the container as the latter is inserted, and then bear on a pistonprovided within the container, such that as the container is inserted,the pusher displaces the piston along the container to create a vacuumin the space between the piston and the membrane.

Further in accordance with the present invention, there is provided acontainer for collecting a sample of blood or other fluid, the containerbeing of tubular form and having one end closed by a piercable membraneand having an internal piston positioned adjacent said membrane.

Embodiments of the present invention will now be described by way ofexamples only and with reference to the accompanying drawings, in which:

FIG. 1 is a side view, partly in section, of a first embodiment ofcannula introducing device in accordance with this invention, shown witha cannula disposed over the needle of the device and the assembly in aninitial condition ready for use;

FIG. 2 is a top plan view of the assembly shown in FIG. 1;

FIG. 3 is a side view of the assembly, corresponding to FIG. 1, showingthe cannula once advanced over the tip of the needle and the devicepartly withdrawn;

FIG. 4 is a similar view of the assembly, once the device has beencompletely withdrawn from the cannula and the plunger of the devicefully advanced to cover the tip of the needle;

FIG. 5 is a view, similar to FIG. 1, of a second embodiment of device inaccordance with the present invention;

FIG. 6 is a view, similar to FIG. 2, of the assembly shown in FIG. 5;

FIG. 7 is a view, similar to FIG. 5, of a third embodiment of device inaccordance with the present invention;

FIG. 8 is a view, similar to FIG. 6, of the assembly shown in FIG. 7;

FIG. 9 is a view similar to FIG. 1, showing a modified embodiment ofcannula introducing device, in an initial condition ready for use;

FIG. 10 is a top plan view of the assembly shown in FIG. 9;

FIG. 11 is a side view of the assembly, corresponding to FIG. 9, showingthe plunger of the cannula introducing device advanced through aninitial distance, to advance the tip of the cannula over the tip of theneedle of the device;

FIG. 12 is a similar view of the assembly, showing the plunger after ithas been advanced its full extent;

FIG. 13 is a side view, similar to FIG. 1, of a further embodiment ofcannula introducing device, shown in an initial condition ready for use;

FIG. 14 is a top plan view of the assembly shown in FIG. 13;

FIG. 15 is a side view of the assembly, corresponding to FIG. 13,showing the plunger of the cannula introducing device advanced throughan initial distance, to advance the tip of the cannula over the tip ofthe needle; and

FIG. 16 is a similar side view of the assembly, showing the plungerafter it has been advanced to its full extent by a spring of the device.

Referring to FIGS. 1 and 2 of the drawings, there is shown a cannulaintroducing device which comprises an elongate body 10 having a hollowneedle 12 projecting from a forward end thereof, the interior of theneedle communicating with a blood collecting chamber 14 within the body10. The device further comprises a plunger 16, in the form of a flatplate, initially disposed against the front end of the body 10 andhaving a central aperture through which the needle 12 extends. A guidegroove 18 is formed along an upper side of the body 10, the groove 18extending from a point adjacent the front end of the body 10 to a pointadjacent the rear end of the body 10, where it joins a passage 20 whichextends though the body 10, firstly curving across the body 10 towardsits lower side and then extending longitudinally of the body 10 to itsfront end. A guide wire 22 extends along the groove 18 and then alongthe passage 20, the guide wire 22 having one end attached to anoperating knob 24 and its other end attached to the plunger 16: theoperating knob 24 is engaged with the groove 18 so as to be slidablealong this groove, whilst being retained by it; also, the operating knob24 projects outwardly from the groove 18, to enable the user to engageit and slide it rearwardly along the groove. The guide wire 22 isresiliently flexible so that, as the operating knob 24 is slidrearwardly of the body 10, the wire will displace along the passage 20and so advance the plunger 16 along the needle 12.

In use, the plunger 16 is initially in the retracted position shown inFIGS. 1 and 2, in contact with the front end of the body 10. A cannula30 is then slipped over the needle 12, for its rear end to abut theplunger 16 and the tip of the needle to project from the forward end ofthe cannula. It will be noted that the cannula 30 comprises a tubularstem having an enlarged, conical rear end. The user grips the body 10 inone hand and brings the assembly up to the patient to insert the needle12 carefully into a blood vessel: then the user engages the operatingknob 24 with his or her index finger, and moves this rearwardly alongits guide groove 18, so displacing the guide wire 22 lengthwise ofitself and along the groove 18 and passage 20, to advance the plunger16; the plunger 16 accordingly pushes the cannula forwardly along theneedle, so that the forward end of the cannula passes over the tip ofthe needle and into the blood vessel.

Once the cannula is in position, and referring to FIGS. 3 and 4 of thedrawings, the body 10 can be withdrawn to withdraw the needle, firstlyfrom the blood vessel and finally from the cannula: throughout thismovement, the rearward displacement of the operating knob 24 iscontinued, so that the plunger 16 continues to advance and, finally,covers the sharp end of the needle 12. Accordingly, the tip of theneedle is covered and possible needle stick injuries are prevented.

The guide wire 22 is formed with a series of ratchet serrations 22 awhich co-operate with a tooth 10 a formed on the body 10 of the device,at or adjacent its front end: this prevents the device being re-used,with the risk of spreading infection.

It will be appreciated that the device which has been described is ofrelatively simple construction yet easy to use, whilst minimising therisk of movement of the needle tip as the cannula is advanced over theneedle and into the blood vessel. The device avoids the use of springsand, moreover, provides for the sharp tip of the needle to becomecovered at the end of the cannulation procedure.

FIGS. 5 and 6 show a device similar to that shown in FIGS. 1 to 4, likeparts being denoted by like reference numerals. The device shown inFIGS. 5 and 6 differs, from that shown in FIGS. 1 to 4, in that the body10 is formed with a pair of interior compartments side-by-side, open tothe rear of the body, to receive respective elongate, blood-collectingcontainers of a unit or cartridge 40. The needle 12 of the devicecommunicates, at its inner end, with an internal chamber 41 of the body10, in which a plunger 42 is disposed, the plunger 42 being formed witha pair of piercing needles 43 for puncturing membranes 44 which closethe ends of the blood-collecting containers of the cartridge 40.Typically, the blood-collecting containers will be pre-evacuated.

In use of the device shown in FIGS. 5 and 6, the cartridge 40 isinserted into the body 10 of the device before the device is brought upto the patient. When the tip of the needle 12 of the device is insertedinto the patient's blood vessel, blood will pass along the needle andinto the chamber 41 at the forward end of the body 10. When the usersees the presence of the blood in this chamber 41 (the wall of body 10being transparent), the operating knob 24 is retracted slightly: thisoperating knob is coupled to the plunger 42 to corresponding retractthis plunger and so cause its piercing needles 43 to pierce the membrane44 at the ends of the blood-collecting containers. The vacuum withinthese containers causes the blood to be drawn into them, through theneedle 12 of the device, its internal chamber 41 and the piercingneedles 43 of the plunger 42. The operating knob is arranged so that,upon further retraction, it advances the plunger 16 of the device and sodisplaces the cannula 30 over the tip of the needle and into the bloodvessel, as above-described with reference to FIGS. 1 to 4 of thedrawings. In a modification, the operating knob 24 serves only fordisplacing the plunger 16 and a secondary operating knob is provided,for example alongside or forwardly of the operating knob 24, forretracting the internal plunger 42. Further, the device body 10 may beformed with an internal membrane which closes the chamber 41, thepiercing needles 43 of the plunger 42 firstly piercing this membrane andthen the membranes 44 of the cartridge 40 when the plunger 42 isretracted.

FIGS. 7 and 8 show a similar device to that shown in FIGS. 5 and 6, likeparts being denoted by like reference numerals. The device of FIGS. 7and 8 differs in that it is arranged to create a vacuum in each of theblood-collecting containers of the cartridge 40. Each of thesecontainers is provided with an internal piston 45, initially positionedadjacent the membrane 44 which closes its forward end. The device body10 is formed internally with a pair of rearwardly-directed posts 46arranged so that, as the cartridge 40 is inserted into the body 10, theposts 46 pierce the membranes 44 of the two containers and abut thepistons 45, and push these pistons rearwardly along the respectivecontainers of the cartridge 40, so creating a vacuum within thecontainers, forwardly of the pistons 45. It will be appreciated that therear ends of the containers are formed with openings to allow air to beexpelled from the spaces to the rear of the pistons 45: also, themembranes 44 maintain a seal around the posts 46 during the forwardmovement of the cartridge 40.

FIGS. 9 to 12 show a modification applicable to each of the deviceswhich have been described above. In this device, the elongate flexibleelement 22 extends from the forward end of the groove or channel inwhich the operating knob 24 is retained, and round in a curve to apassage extending lengthwise of the body 10 adjacent the side or edge ofthe body 10, opposite the side in which the groove for the operatingknob 24 is formed. The plunger 16 has a rearwards extension 17 to theend of which the element 22 is coupled. Thus, as the operating knob 24is displaced rearwardly, the element 22 is displaced longitudinally ofitself to pull on the extension 17 of the plunger 16 and so pull theplunger forwardly.

FIGS. 13 to 16 show a further embodiment which corresponds generally tothe embodiment of FIGS. 1 to 4 and incorporating the modification ofFIGS. 9 to 12, but also incorporating an additional modification. Thus,retraction of the operating knob 24 serves to pull the plunger 16forwardly through an initial distance, sufficient to advance the tip ofthe cannula 30 over the tip of the needle 12 and so introduce the tip ofthe cannula 30 into the blood vessel (see FIG. 15). The device furtherincludes a compression spring 50, or alternatively a compressed airspring, positioned around the blood collecting chamber 14: at the end ofits retracting movement for advancing the plunger 16 over its initialdistance as just described, the operating knob 24 serves to actuate orrelease the spring 50, which then acts on sliding mounting elements 19of the plunger 16 to advance this fully, until the plunger 16 covers thetip of the needle 12. This final advancement of the plunger 16 is swiftand serves to advance the cannula the required distance into the bloodvessel, the plunger protecting the tip of the needle 12 (FIG. 16). Itwill also be noted that the mounting elements 19 of the plunger areelongate in form and extend parallel to the needle 12 and are spacedapart around it, so as to enclose the needle 12 and provide furtherprotection for it, in the extended condition of the plunger.

1. A cannula introducing device which comprises an elongate body havinga needle projecting from one end thereof, an operating element mountedto said body for displacement longitudinally thereof, a plunger disposedat said one end of said body, and means coupling said operating elementand said plunger and arranged so that displacement of said operatingelement away from said one end of said body causes displacement of saidcoupling means to advance said plunger along said needle.
 2. A device asclaimed in claim 1, arranged for said plunger to be displaceable, bydisplacement of said operating element, far enough to cover the tip ofsaid needle.
 3. A device as claimed in claim 1, arranged for saidplunger to be advanced an initial distance by said displacement of saidoperating element, the device further comprising a spring serving toadvance said plunger through a further distance.
 4. A device as claimedin any preceding claim, including means for preventing said plungerbeing retracted after having been advanced along said needle.
 5. Adevice as claimed in any preceding claim, in which said coupling meanscomprises an elongate flexible element which extends along a guideway ofsaid body, between said operating element and said plunger, and arrangedto be displaced longitudinally of itself as said operating element isdisplaced.
 6. A device as claimed in claim 5, in which said flexibleelement is arranged to push said plunger forwardly along said needle. 7.A device as claimed in claim 5, in which said flexible element isarranged to pull said plunger forwardly along said needle.
 8. A deviceas claimed in claim 6, in which said guideway comprises a groove orchannel formed in said body, said operating element being engaged intosaid groove or channel for sliding movement along it.
 9. A device asclaimed in claim 8, in which said operating element comprises a memberwhich projects outwardly from said groove or channel, for the user toengage manually.
 10. A device as claimed in any one of claims 5, 6, 8 or9, in which said guideway further comprises a passage having a firstportion which extends from the rear end of said groove or channel andcurves round to a second portion which extends forwardly to said one endof said body.
 11. A device as claimed in claim 10, in which said secondportion of said guideway is disposed in or adjacent a surface of saidbody remote from or opposite a surface in which said guide groove orchannel is formed.
 12. A device as claimed in any one of claims 5 to 11,in which said coupling means comprises a wire.
 13. A device as claimedin claim 12, in which said wire is of a flat cross-sectional profile.14. A device as claimed in any preceding claim, in which said body isarranged to receive a fluid-collecting container for receiving blood orother fluid through said needle.
 15. A device as claimed in claim 14, inwhich said body includes an internal chamber to receive blood or otherfluid through said needle, said chamber being provided with a plungerwhich is displaced upon retraction of said operating element, or of asecondary operating element, for a piercing needle of said plunger topierce a membrane closing the end of said fluid-collecting container.16. A device as claimed in claim 14 or 15, in which said body is formedwith an elongate compartment for the longitudinal insertion of a saidcontainer of tubular form, said compartment being provided with alongitudinal member for piercing said membrane of said container and tobear on and displace an internal piston of said container, as saidcontainer is inserted into said compartment.
 17. A device as claimed inany one of claims 14 to 16, in combination with a said fluid-collectingcontainer inserted into or for insertion into said body.
 18. A device asclaimed in any preceding claim, in combination with a cannula receivedover said needle.
 19. A device for collecting a sample of blood or otherfluid, the device comprising an elongate body having a needle projectingfrom one end thereof, the body having an interior compartment forreceiving a fluid-collecting container and having a plunger disposedtherein, the device further comprising an operating element arranged fordisplacement longitudinally of said body away from said one end thereof,in order to displace said plunger and for a piercing needle provided onsaid plunger to pierce a membrane which closes said container.
 20. Adevice as claimed in claim 19, in combination with a fluid collectingcontainer received or for receiving within said body.
 21. A containerfor collecting a sample of blood or other fluid, the container being oftubular form and having one end closed by a piercable membrane andhaving an internal piston positioned adjacent said membrane.